Many online shoppers were taken aback when Amazon raised the price of its Prime service. Although Prime offers a streaming video service, many customers have come to rely on its free two-day shipping.

Some took the $20 price hike in stride. But if you're annoyed, and looking for alternatives, there are cheaper versions you can try.

Rivals, including ShopRunner, Overstock.com and Newegg, offer online shoppers free shipping on a wide range of products. Their annual fees are all less than the $99 annual price tag for Amazon Prime.

ShopRunner pounced on the price increase. The company, which guarantees its members free two-day shipping on merchandise from more than 85 online retailers, began offering Amazon Prime customers free membership for a year.

ShopRunner usually charges $79 a year. American Express cardholders can also get the service for free. That's because the credit card company is one of ShopRunner's financial backers.

ShopRunner's retail partners are diverse enough that it could be a substitute for Amazon Prime. ShopRunner members can get free shipping when they buy toys online from Toys R Us, cosmetics from Drugstore.com, vitamins from GNC, or clothing from Brooks Brothers, Neiman Marcus and American Eagle Outfitters. If an item qualifies for free shipping through ShopRunner, members sign into their accounts before checking out and the shipping costs disappear.

The promotion for Amazon Prime members is only for a limited time, but there's no end date yet, said Fiona Dias, ShopRunner's chief strategy officer.

At Overstock.com, members of its Club O program are charged $19.95 a year to get free shipping on everything from TVs to blenders to shampoos. But unlike Prime and ShopRunner, Club O doesn't guarantee how fast products will arrive. However, there are other benefits. Members get 5 percent back on every order, which they can use to spend on future Overstock purchases.

Newegg, which sells computer parts, tablets, clothing and cosmetics, launched its free shipping program in February. Newegg Premier charges $49.99 a year for free shipping within three days on some of the items it sells.

If you make several purchases of one particular type of item, be sure to look into what specialized retailers offer. For instance, book lovers can turn to Barnes & Noble. The bookseller charges $25 a year for its program, which gives its members free, fast shipping for items bought online. Members also get discounts in stores.

Of course, if you're not shopping online frequently enough, the membership fees can be a waste of money. If your purchases tend to be inexpensive, another way to score free shipping is to order enough items to qualify for it. At Amazon, you'll need to buy $35 worth of stuff. The minimum is $50 at Walmart.com and $25 at BarnesandNoble.com. At Target.com, customers who have the retailer's RedCard debit or credit cards get free shipping and 5 percent off their orders.